DATASHEET
ISL78113A
Low Input Voltage and High Efficiency Synchronous Boost Converter with 1.3A
Switch
The ISL78113A provides a tiny and convenient boost power
supply solution to generate a regulated output up to 500mA
from any sub-5V secondary rail found in an automotive
electrical system, including battery powered applications
(NiCd, NiMH, or one-cell Li-Ion/Li-Polymer). It offers an
adjustable output (3.0V to 5.2V) supporting USB-OTG or HDMI
applications. The device is able to supply 500mA from a 3V
input and 5V output, and has a typical 1.3A peak current limit.
The ISL78113A is a fully integrated, internally compensated,
synchronous converter optimized to maximize efficiency and
reduce the overall solution size and bill of materials. Its high
2MHz switching frequency allows the use of tiny, low-profile
inductors and chip capacitors. It also eliminates potential
interference within the AM radio band and the external EMI
filtering needed for converters switching at lower rates. To
minimize power consumption while off, the device features an
ultra-low current shutdown mode dropping quiescent current
to 50nA typical.
ISL78113A is supplied in an 8 Ld DFN package. The device is
rated to operate over the temperature range of -40°C to
+105°C.
FN8638
Rev 0.00
May 1, 2014
Features
• Output disconnect during shutdown preventing output
precharging and uncontrolled short-circuit current
• Input voltage range: 0.8V to 4.7V
• Output current: Up to 500mA (V
BAT
= 3V, V
OUT
= 5V)
• Logic control shutdown (I
Q
< 1µA)
• 2MHz switching frequency
• Up to 95% efficiency at typical operating conditions
• Fault protection: OVP, OCP, OTP, UVLO
• 2mmx2mm 8 Ld DFN package
• Qualified for automotive operations
Applications
• Automotive head units and infotainment systems: especially
those including portable HDMI and USB-OTG connectivity
• Automotive camera systems
100
6.8 µH
90
80
8
V
BAT
= 3.6V
EFFICIENCY (%)
V
BAT
=
0.8V TO 4.7V
7
10µF
5
EN
V
BAT
SW
V
OUT
2
V
OUT
=
5.0V/500mA
70
60
50
40
30
20
10
0
0
V
BAT
= 4.2V
V
BAT
= 3.4V
V
BAT
= 3V
10µF
422
4
FB
80.6
1
GND
V
BAT
= 2.3V
0.1
0.2
0.3
0.4
0.5
0.6
ISL78113AARAZ
LOAD CURRENT I
LOAD
(A)
FIGURE 1. TYPICAL APPLICATION
FIGURE 2. EFFICIENCY vs LOAD CURRENT
FN8638 Rev 0.00
May 1, 2014
Page 1 of 12
ISL78113A
Block Diagram
C1
V
BAT
7
V
OUT
2
C2
UVLO
V
INT
VOLTAGE
SELECTOR
START-UP
GATE
DRIVER
V
OUT
OVP
AND
ANTI-CROSS
CONDUCTION
SW
V
OUT
CURRENT
SENSE
N-WELL
SWITCH
8
SW
L1
EN
5
OFF ON
CONTROL LOGIC
ZCD
R1
AND
DIGITAL
SOFT-START
CURRENT
LIMIT
SLOPE COMP
FB
4
g
m
FAULT
MONITORING
2MHz
OSCILLATOR
THERMAL
SHUTDOWN
1
6
FN8638 Rev 0.00
May 1, 2014
V
INT
VOLTAGE
CLAMP
R2
REFERENCE
GENERATOR
Page 2 of 12
ISL78113A
Pin Configuration
ISL78113A
ADJUSTABLE OUTPUT
(8 LD DFN)
TOP VIEW
1
2
3
4
8
7
6
5
SW
V
BAT
AGND
EN
PGND
V
OUT
NC
FB
Pin Descriptions
PIN
NUMBERS SYMBOL
1
2
3
4
5
PGND
V
OUT
NC
FB
EN
Power ground.
Device output.
No connection.
Feedback pin of the converter. Connect voltage divider resistors between V
OUT
, FB and GND for desired output.
The EN pin is an active-HIGH logic input for enabling the device. When asserted HIGH, the boost function begins. When driven
LOW, the device is completely disabled, and current is blocked from flowing from the SW pin to the output and vice versa. This
pin may be tied either HIGH to enable the device or LOW to disable.
Analog ground.
Device input supply from a battery. Connect a 10µF ceramic capacitor from VBAT to power ground.
The SW pin is the switching node of the power converter. Connect one terminal of the inductor to the SW pin and the other to
power input.
The exposed pad must be connected to PGND pin for proper electrical performance. Place as many vias as possible under the
pad connecting to the system GND plane for optimal thermal performance.
PIN DESCRIPTION
6
7
8
AGND
V
BAT
SW
EPAD
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
ISL78113AARAZ-T
NOTES:
1. Use “-T7A” suffix for 250 pieces tape and reel. Please refer to Tech Brief
TB347
for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil
Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for
ISL78113A.
For more information on MSL please see Tech Brief
TB363.
PART MARKING
AAR
V
OUT
(V)
Adjustable
TEMP RANGE
(°C)
-40 to +105
PACKAGE
(Pb-free)
8 Ld DFN
PKG.
DWG. #
L8.2x2D
FN8638 Rev 0.00
May 1, 2014
Page 3 of 12
ISL78113A
Absolute Maximum Ratings
V
BAT
, EN, V
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
SW Voltage
DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 6.5V
Pulse <10ns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 8.0V
ESD Ratings
Human Body Model (Tested per AEC-Q100-002) . . . . . . . . . . . . . . . . 4kV
Machine Model (Tested per AEC-Q100-003) . . . . . . . . . . . . . . . . . . . 300V
Charged Device Model (Tested per AEC-Q100-011). . . . . . . . . . . . .2.2kV
Latch Up (Tested per AEC-Q100-004; Class II, Level A) . . . . . . . . . . . 15mA
Thermal Information
Thermal Resistance (Typical)
JA
(°C/W)
JC
(°C/W)
8 Ld DFN Package (Notes 4, 5). . . . . . . . . .
80
15
Maximum Junction Temperature (plastic package). . . . . . . . . . . . .+150°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TB493
Recommended Operating Conditions
V
BAT
(after start-up) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8V to 4.7V
V
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (V
BAT
+ 0.2V) to 5.2V
Operating Junction Temperature Range . . . . . . . . . . . . . .-40°C to +125°C
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-40°C to +105°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4.
JA
is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief
TB379.
5. For
JC
the “case temp” location is the center of the exposed metal pad on the package underside.
Electrical Specifications
-40°C to +105°C.
PARAMETER
Start-up Voltage
Input Undervoltage Lockout
Feedback Voltage
Output Voltage
Feedback Pin Input Current
Quiescent Current from V
OUT
Shutdown Current from V
BAT
Leakage Current at SW Pin
N-Channel MOSFET ON-resistance
P-Channel MOSFET ON-resistance
N-Channel MOSFET Peak Current Limit
Maximum Duty Cycle
PWM Switching Frequency
EN Logic High
EN Logic Low
Soft Start-up Time
Load Regulation
Line Regulation
Minimum SW Low in PWM Mode
Output Overvoltage Protection Threshold
Thermal Shutdown
Thermal Shutdown Hysteresis
NOTES:
V
BAT
= 3.0V, V
OUT
= 5V, L = 4.7µH, T
A
= +25°C. Boldface limits apply over the operating temperature range,
MIN
(Note 6)
0.6
0.66
784
V
BAT
= 2V
I
Q1
I
SD
V
BAT
= V
EN
= 1.2V, no load (Note 7)
V
EN
= 0V, V
BAT
= 1.2V, V
O
= 0
V
EN
= 0V, V
BAT
= 4.7V, V
O
= 0
0.20
0.35
I
PK
D
MAX
F
OSC
2.5V < V
BAT
< 4.7V
V
BAT
< 2.5V
2.5V < V
BAT
< 4.7V
V
BAT
< 2.5V
C
OUT
= 4.7μF, L = 4.7μH
ΔV
OUT
/V
OUT
t
MIN(ON)
T
SD
I
LOAD
= 1 to 50mA
V
BAT
= 3.0V to 3.6V, I
LOAD
= 1mA
-0.5
-0.5
0.2
±0.01
±0.03
42
5.9
150
25
1
82
1.73
1.2
0.48*V
BAT
0.35
0.14*V
BAT
1
0.5
0.5
49
1.3
87.5
2
2.23
1.6
3.0
-100
5.5
0.05
MAX
(Note 6)
0.9
0.76
816
5.2
100
10
2.8
15
SYMBOL
V
MIN
V
UVLO
V
FB
TEST CONDITIONS
V
EN
= 1.2V, R
LOAD
= 50Ω
V
EN
= V
BAT,
R
LOAD
= 50Ω
TYP
0.75
0.70
800
UNITS
V
V
mV
V
nA
mA
μA
μA
Ω
Ω
A
%
MHz
V
V
V
V
ms
%
%
ns
V
o
C
o
C
6. Compliance to datasheet limits is assured by one or more methods: production test, characterization and/or design.
7. I
Q1
is measured at V
OUT
and multiplied by V
OUT
/V
BAT
; thus, the equivalent input quiescent current is calculated.
FN8638 Rev 0.00
May 1, 2014
Page 4 of 12
ISL78113A
Detailed Description
Current Mode PWM Operation
The control scheme of the device is based on the peak current
mode control and the control loop is compensated internally. The
peak current of the N-channel MOSFET switch is sensed to limit
the maximum current flowing through the switch and the
inductor. The typical current limit is set to 1.3A.
The control circuit includes a current ramp generator, slope
compensator, error amplifier and a PWM comparator (see the
“Block Diagram” on page 2). The ramp signal is derived from the
inductor current. This ramp signal is then compared to the error
amplifier output to generate the PWM gating signals for driving
both N-channel and P-channel MOSFETs. The PWM operation is
initialized by the clock from the internal oscillator (typical 2MHz).
The N-channel MOSFET is turned ON at the beginning of a PWM
cycle, the P-channel MOSFET remains OFF, and the current starts
ramping up. When the sum of the ramp and the slope
compensator output reaches the error amplifier output voltage,
the PWM comparator outputs a signal to turn OFF the N-channel
MOSFET. Here, both MOSFETs remain OFF during the dead-time
interval. Next, the P-channel MOSFET is turned ON and remains
ON until the end of this PWM cycle. During this time, the inductor
current ramps down until the next clock. At this point, following a
short dead time, the N-channel MOSFET is again turned ON,
repeating as previously described.
to the current limit value (typically 1.3A) during the soft-start
period to limit in-rush current from the input source. Fault
monitoring begins approximately 2ms after the device is
enabled.
To start up with a slow V
BAT
ramp-up rate is likely to cause the
device to enter hiccup mode. This is a result of the input voltage
dropping due to start-up current, which causes a fault of V
OUT
out
of regulation, especially at high load and cold temperature.
Check the input ramp-up rate and a faster input slew rate would
help to resolve this.
Over-temperature Protection (OTP)
The device offers over-temperature protection. A temperature
sensor circuit is integrated and monitors the internal IC
temperature. Once the temperature exceeds the preset threshold
(typically +150°C), the IC shuts down immediately. The OTP has
a typical hysteresis of +25°C. When the device temperature
decreases by this, the device starts operating.
Synchronous Rectifier
The ISL78113A integrates one N-channel MOSFET and one
P-channel MOSFET to realize a synchronous boost converter.
Because the commonly used discrete Schottky rectifier is
replaced with the low r
DS(ON)
P-channel MOSFET, the power
conversion efficiency reaches a value above 90%.
V
OUT
Isolation
Since a typical step-up converter has a conduction path from the
input to the output via the body diode of the P-channel MOSFET,
a special circuit (see the “Block Diagram” on page 2) is used to
reverse the polarity of the P-channel body diode when the device
is shut down. Thus, this configuration completely disconnects the
load from the input during shutdown of the converter. The benefit
of this feature is that the battery will not be completely depleted
during shutdown of the converter. No additional components are
needed to disconnect the battery from the output of the
converter.
Soft-Start
The soft start-up duration is the time between the device being
enabled and V
OUT
rising to within 3% of the target voltage. When
the device is enabled, the start-up cycle starts with a linear
operating phase. During the linear phase, the rectifying switch is
turned ON in a current limited configuration, delivering about
350mA, until the output capacitor is charged to approximately
90% of the input voltage. At this point, PWM operation begins in
boost mode. If the output voltage is below 2.3V, PWM switching
is done at a fixed duty-cycle of 75% until the output voltage
reaches 2.3V. When the output voltage exceeds 2.3V, the
closed-loop current mode PWM loop overrides the duty cycle until
the output voltage is regulated. Peak inductor current is ramped
FN8638 Rev 0.00
May 1, 2014
Page 5 of 12
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
